Start of mux method

frame.go

@@ -71,6 +71,11 @@ func (frame *frame) Type() MediaType {
 	return NONE
 }
 
+// Id is unused
+func (frame *frame) Id() int {
+	return 0
+}
+
 // Return the timestamp as a duration, or minus one if not set
 func (frame *frame) Time() time.Duration {
 	pts := frame.ctx.Pts()

interfaces.go

@@ -140,8 +140,14 @@ type Media interface {
 	// Return a decoding context for the media stream, and
 	// map the streams to decoders. If no function is provided
 	// (ie, the argument is nil) then all streams are demultiplexed.
+	// Will return an error if called on a writer.
 	Decoder(DecoderMapFunc) (Decoder, error)
 
+	// Multiplex media into packets. Pass a packet to a muxer function.
+	// Stop when the context is cancelled or the end of the media stream is
+	// signalled. Will return an error if called on a reader.
+	Mux(context.Context, MuxFunc) error
+
 	// Return INPUT for a demuxer or source, OUTPUT for a muxer or
 	// sink, DEVICE for a device, FILE for a file or stream.
 	Type() MediaType
@@ -191,6 +197,9 @@ type Parameters interface {
 	// Return the media type (AUDIO, VIDEO, SUBTITLE, DATA)
 	Type() MediaType
 
+	// Return the stream id for encoding, or zero if not set
+	Id() int
+
 	// Return number of planes for a specific PixelFormat
 	// or SampleFormat and ChannelLayout combination
 	NumPlanes() int
@@ -224,6 +233,10 @@ type VideoParameters interface {
 // io.EOF if you want to stop processing the packets early.
 type DecoderFunc func(Packet) error
 
+// MuxFunc is a function that multiplexes a packet. Return
+// io.EOF to stop multiplexing normally.
+type MuxFunc func(Packet) error
+
 // FrameFunc is a function that processes a frame of audio
 // or video data.  Return io.EOF if you want to stop
 // processing the frames early.

parameters.go

@@ -23,6 +23,9 @@ type par struct {
 type codecpar struct {
 	Codec ff.AVCodecID `json:"codec"`
 
+	// Stream Id
+	StreamId int `json:"stream_id"`
+
 	// For video (in fps)
 	Framerate float64 `json:"framerate"`
 }
@@ -168,6 +171,11 @@ func (par *par) Type() MediaType {
 	return par.t
 }
 
+// Return stream id
+func (par *par) Id() int {
+	return par.codecpar.StreamId
+}
+
 // Return number of planes for a specific PixelFormat
 // or SampleFormat and ChannelLayout combination
 func (par *par) NumPlanes() int {

reader.go

@@ -1,6 +1,7 @@
 package media
 
 import (
+	"context"
 	"encoding/json"
 	"errors"
 	"io"
@@ -9,6 +10,9 @@ import (
 
 	// Packages
 	ff "github.com/mutablelogic/go-media/sys/ffmpeg61"
+
+	// Namespace imports
+	. "github.com/djthorpe/go-errors"
 )
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -229,6 +233,10 @@ func (r *reader) Metadata(keys ...string) []Metadata {
 	return result
 }
 
+func (r *reader) Mux(context.Context, MuxFunc) error {
+	return ErrOutOfOrder.With("not an output stream")
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // PRIVATE METHODS
 

writer.go

@@ -1,6 +1,7 @@
 package media
 
 import (
+	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -67,11 +68,18 @@ func createMedia(url string, format Format, metadata []Metadata, params ...Param
 	// Add encoders and streams
 	var result error
 	for i, param := range params {
-		encoder, err := newEncoder(ctx, i, param)
+		// Stream Id from codec parameters, or use the index
+		stream_id := param.Id()
+		if stream_id <= 0 {
+			stream_id = i + 1
+		}
+		encoder, err := newEncoder(ctx, stream_id, param)
 		if err != nil {
 			result = errors.Join(result, err)
+		} else if _, exists := writer.encoder[stream_id]; exists {
+
 		} else {
-			writer.encoder[i] = encoder
+			writer.encoder[stream_id] = encoder
 		}
 	}
 
@@ -143,16 +151,15 @@ func (w *writer) Close() error {
 		result = errors.Join(result, encoder.Close())
 	}
 
-	// Free resources
-	if w.metadata != nil {
-		ff.AVUtil_dict_free(w.metadata)
-	}
+	// Free output resources
 	if w.output != nil {
+		// This calls avio_close(w.avio)
 		result = errors.Join(result, ff.AVFormat_close_writer(w.output))
 	}
-	if w.avio != nil {
-		fmt.Println("TODO AVIO")
-		//		result = errors.Join(result, ff.AVFormat_avio_close(w.avio))
+
+	// Free resources
+	if w.metadata != nil {
+		ff.AVUtil_dict_free(w.metadata)
 	}
 
 	// Release resources
@@ -183,7 +190,46 @@ func (w *writer) String() string {
 // PUBLIC METHODS
 
 func (w *writer) Decoder(DecoderMapFunc) (Decoder, error) {
-	return nil, ErrNotImplemented
+	return nil, ErrOutOfOrder.With("not an input stream")
+}
+
+func (w *writer) Mux(context.Context, MuxFunc) error {
+	return ErrNotImplemented
+
+	/*
+			while (1) {
+		        AVStream *in_stream, *out_stream;
+
+		        ret = av_read_frame(ifmt_ctx, pkt);
+		        if (ret < 0)
+		            break;
+
+		        in_stream  = ifmt_ctx->streams[pkt->stream_index];
+		        if (pkt->stream_index >= stream_mapping_size ||
+		            stream_mapping[pkt->stream_index] < 0) {
+		            av_packet_unref(pkt);
+		            continue;
+		        }
+
+		        pkt->stream_index = stream_mapping[pkt->stream_index];
+		        out_stream = ofmt_ctx->streams[pkt->stream_index];
+		        log_packet(ifmt_ctx, pkt, "in");
+
+		        // copy packet
+		        av_packet_rescale_ts(pkt, in_stream->time_base, out_stream->time_base);
+		        pkt->pos = -1;
+		        log_packet(ofmt_ctx, pkt, "out");
+
+		        ret = av_interleaved_write_frame(ofmt_ctx, pkt);
+		        // pkt is now blank (av_interleaved_write_frame() takes ownership of
+		        // its contents and resets pkt), so that no unreferencing is necessary.
+		        // This would be different if one used av_write_frame().
+		        if (ret < 0) {
+		            fprintf(stderr, "Error muxing packet\n");
+		            break;
+		        }
+		    }
+	*/
 }
 
 // Return OUTPUT and combination of DEVICE and STREAM

writer_test.go

@@ -22,7 +22,7 @@ func Test_writer_001(t *testing.T) {
 	}
 
 	// Write audio file
-	filename := filepath.Join(t.TempDir(), t.Name()+".sw")
+	filename := filepath.Join(t.TempDir(), t.Name()+".mp3")
 	stream, err := manager.AudioParameters("mono", "s16", 22050)
 	if !assert.NoError(err) {
 		t.SkipNow()
@@ -33,5 +33,5 @@ func Test_writer_001(t *testing.T) {
 		t.SkipNow()
 	}
 	defer writer.Close()
-	t.Log(writer)
+	t.Log(writer, "=>", filename)
 }